牵引电动机架悬式有何优缺点?在机车上有什么应用?

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问题:

牵引电动机架悬式有何优缺点?在机车上有什么应用?

考点:电力机车钳工电力机车钳工(高级技师)电力机车钳工(高级技师)题库
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已知O是锐角三角形△ABC的外接圆的圆心,且∠A=θ,若
cosB
sinC
AB
+
cosC
sinB
AC
=2m
AO
,则m=(  )
A.sinθB.cosθC.tanθD.不能确定
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叶片的表皮有哪些特点是与光合作用相适应的(  )

①表皮细胞无色透明;②表皮细胞排列疏松,能透过气体;③表皮细胞外壁具有透明的角质层;④表皮上有由保卫细胞构成的气孔.

A.①②③

B.①③④

C.②③④

D.①②④

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阅读理解。

      Winston Churchill was born into a famous family. His father was a successful politician. However, as a

boy, Churchill was considered a slow learner in school.

     Later he entered the Army and saw action in various countries.

     In October 1900, Churchill began his political career. For the next sixty years Churchill's work as a great

politician was both brighter and more difficult than his father had been.

     In 1939, Germany attacked Poland. Churchill prepared to fight. In 1940 he became the Prime Minster of

England.

     France fell. The Germans fought their way through Western Europe. It looked as if Britain was about to

lose the war. Was it not possible to ask for peace, and listen to Hitler?

     Churchill spoke, "I have nothing to offer but blood, hard work, tears and sweat (汗)...You ask what is our

policy (政策)? I will tell you, it is to fight, by sea, by land and air, with all our force and with all the strength

that God can give us. You ask what is our aim? I can answer in one word: victory."

     The Germans began moving their armies to the French coast and prepared to go to war with the British.

The British had not enough guns to go round. Churchill gave the answer:"We shall defend our island, whatever

the cost may be, we shall fight on the coasts, we shall fight on the landing grounds, we shall fight in the field

and in the streets, we shall fight in the hills, we shall never give up." 

     By his courage and hard work Churchill heartened his people and other nations fighting together against

Hitler. Victory finally came when the Germans lost World War Ⅱ.

     Churchill died in 1965 and was given a State Funeral (国葬). This was a fitting payment to one of all the

greatest men the world had ever seen.

1. Churchill _____ before he became a politician.

A. was a slow student

B. was an army man

C. helped his father in his career (职业; 生涯)

D. had little interest in politics

2. The Germans attacked Britain _____.

A. after France was defeated

B. before French fell

C. soon after Poland was attacked

D. before Churchill became the Prime Minister

3. The underlined word "heartened" probably means _____ in this passage.

A. surprised

B. encouraged

C. asked for

D. called for

4. Which of the following is NOT true?

A. Churchill had worked as a politician for more than sixty years.

B. The writer admired and respected Churchill very much.

C. Churchill was not so clever as his father.

D. Churchill was one of the most inspiring, brave and wise leaders in the British history.

5. We can infer from the passage that _____.

A. finally Hitler had to give in to Churchill

B. Churchill asked to be given a State Funeral before he died

C. the countries which won World War II held a State Funeral in honor of the statesman

D. Churchill was a man of great determination

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钢筋冷拉时,如果采用应力控制法,当冷拉应力为σ,冷拉率为S,下列哪种情况是合格的?()

A.S达控制值,σ未达控制值

B.σ达控制值,S超过规定值

C.S未达控制值,σ达控制值

D.σ未达控制值,S未超过规定值

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简述前置胎盘的主要症状。

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